Airox process

In the AIROX processing system, the hardware is sheared off the ends of the fuel assembly and individual fuel pins are fed into a continuous rotary punch, which is essentially a V-belt pulley with punch dies extended from the center of the groove. 

This provides small holes in the fuel pins spaced at an optimum distance (2.5 to 4.0 cm apart) to permit gaseous reactant (O2 and H2) access to the fuel. The cladding after AIROX processing is shown in Figure 1. A typical-size distribution of fuel particles... 

TYPICAL SIZE DISTRIBUTION OF AIROX PROCESSED FUEL... 

FBR Cycle. The AIROX process is also applicable to FBR fuel recycle The FBR driver fuel must be enriched in fissile content... 

In the FBR fuel cycles, the fraction (i.e., 21% in the examples above) of the blanket fuel recycled for use in refabricating driver fuel after AIROX processing only depends on the concentration of fissile material in the Civex or Pyrocivex product. As the fissile content of the Civex or Pyrocivex product is decreased, the amount of blanket fuel recycled for driver fuel fabrication must also be decreased proportionately and the amount of spent blanket fuel processed by the Civex or Pyrocivex process must be increased. 

Potential diversion of nuclear material from power production to weapons production by national or subnational groups has resulted in a reevaluation of the proliferation resistance of various fuel cycles. The low-contamination fuel cycle, utilizing AIROX dry processing, is proliferation resistant due to the retention of fission products with the fuel and to the low concentration of fissile material in all process steps. In the AIROX process, UO2 is oxidized with air to U3O8 to expand the fuel volume which simultaneously declads and pulverizes the fuel the fuel is subsequently reenriched, repelletized, and recycled to the reactor. 

There remains the question of how to come by the first core loading without separation of Pu. One possibility [XX-8, XX-33] is to use LWR spent fuel as the feed material and to remove from it only part of the uranium and part or all of the FP. For example, if the LWR spent fuel contains 1% Pu and minor activities (MA), it is necessary to remove approximately 90% of the uranium to make a fuel with 11 to 12 % of Pu and MA by weight. This could hopefully be done using a highly proliferation-resistant process, possibly a combination of an AIROX process and a fluoride volatilization process or a simplified version of the UREX process. Another feed option that could be considered is the spent fuel from MOX fuelled LWRs. The transuranium isotopes (TRU) content in such spent fuel can be approximately half of that needed for ENHS like reactors. Hence, only -50% of the uranium need be extracted along with FP to make fuel for ENHS like reactor. The latter is likely to offer a more economical fuel cycle. 

FEINROTH, H., GUON, J., MAJUMDAR, D., An overview of the AIROX process and its potential for nuclear fuel recycle, (Paper presented at the Global Int. Fuel Cycle Conf, Seattle, 1993). 

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